Kezia Dugdale has put an end to two turbulent years as leader of Scottish Labour, saying it is time to “pass on the baton” to someone else.
Ms Dugdale, who was born in Aberdeen and lived in Elgin, has previously criticised UK leader Jeremy Corbyn and has come under fire from left-wing members of her own party.
But she insists she is leaving Scottish Labour in a better state than she found it.
The 36-year-old said a new leader was needed with “fresh energy, drive and a new mandate” as she stepped down with immediate effect.
She said she wanted to give her successor the “space and time” to prepare for the next Scottish Parliament election in 2021.
Her resignation letter was published online tonight.
Ms Dugdale wrote: “It has been an honour and a privilege to have served this party in a leadership position for the last two-and-a-half years, covering four national elections and one referendum.
“Being leader has always been a difficult but fulfilling challenge. One that until now I have enjoyed, driven by a clear guiding purpose and goals, many of which I have achieved.
“A marker of success for me was to leave as leader with the party in better shape than I found it and I have done that.
Emerging from the challenging times following the 2014 referendum, and the 2015 UK election, we now have a solid platform on which to build towards success, and government.
“I have given the task of achieving this all that I have. But with nearly four years now until the next Scottish Parliament elections, I am convinced that the party needs a new leader with fresh energy, drive and a new mandate to take the party into that contest.”
Ms Dugdale will continue as Labour MSP for the Lothians.
She replaced Jim Murphy as Scottish Labour leader in August 2015, after the party lost all but one of its Westminster seats in Scotland to the SNP.
Under her leadership, Labour finished third behind the SNP and Scottish Conservatives in last year’s Scottish Parliament election – but went on to win seven seats in the snap general election in June.